全文获取类型
收费全文 | 535117篇 |
免费 | 57601篇 |
国内免费 | 754篇 |
专业分类
593472篇 |
出版年
2018年 | 6319篇 |
2017年 | 5949篇 |
2016年 | 8458篇 |
2015年 | 12364篇 |
2014年 | 13806篇 |
2013年 | 18586篇 |
2012年 | 22206篇 |
2011年 | 22198篇 |
2010年 | 14539篇 |
2009年 | 12566篇 |
2008年 | 19219篇 |
2007年 | 19593篇 |
2006年 | 18231篇 |
2005年 | 17330篇 |
2004年 | 17109篇 |
2003年 | 15919篇 |
2002年 | 15245篇 |
2001年 | 20440篇 |
2000年 | 20396篇 |
1999年 | 16425篇 |
1998年 | 6233篇 |
1997年 | 6117篇 |
1996年 | 5794篇 |
1995年 | 5585篇 |
1994年 | 5314篇 |
1993年 | 5194篇 |
1992年 | 13420篇 |
1991年 | 13312篇 |
1990年 | 12955篇 |
1989年 | 12397篇 |
1988年 | 11508篇 |
1987年 | 10770篇 |
1986年 | 10278篇 |
1985年 | 10113篇 |
1984年 | 8404篇 |
1983年 | 7284篇 |
1982年 | 5488篇 |
1981年 | 4984篇 |
1980年 | 4610篇 |
1979年 | 7797篇 |
1978年 | 6322篇 |
1977年 | 5619篇 |
1976年 | 5275篇 |
1975年 | 6102篇 |
1974年 | 6653篇 |
1973年 | 6480篇 |
1972年 | 5713篇 |
1971年 | 5335篇 |
1970年 | 4503篇 |
1969年 | 4421篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
HIF-1 expression in healing wounds: HIF-1alpha induction in primary inflammatory cells by TNF-alpha 总被引:12,自引:0,他引:12
82.
The cell surface of the parasitic protozoan Leishmania mexicana is coated by glycosylphosphatidylinositol (GPI)-anchored glycoproteins, a GPI-anchored lipophosphoglycan and a class of free GPI glycolipids. To investigate whether the anchor or free GPIs are required for parasite growth we cloned the L.mexicana gene for dolichol-phosphate-mannose synthase (DPMS) and attempted to create DPMS knockout mutants by targeted gene deletion. DPMS catalyzes the formation of dolichol-phosphate mannose, the sugar donor for all mannose additions in the biosynthesis of both the anchor and free GPIs, except for a alpha1-3-linked mannose residue that is added exclusively to the free GPIs and lipophosphoglycan anchor precursors. The requirement for dolichol-phosphate-mannose in other glycosylation pathways in L.mexicana is minimal. Deletion of both alleles of the DPMS gene (lmdpms) consistently resulted in amplification of the lmdpms chromosomal locus unless the promastigotes were first transfected with an episomal copy of lmdpms, indicating that lmdpms, and possibly GPI biosynthesis, is essential for parasite growth. As evidence presented in this and previous studies indicates that neither GPI-anchored glycoproteins nor lipophosphoglycan are required for growth of cultured parasites, it is possible that the abundant and functionally uncharacterized free GPIs are essential membrane components. 相似文献
83.
Sebastián Moran Miguel Vizoso Anna Martinez-Cardús Antonio Gomez Xavier Matías-Guiu Sebastián M Chiavenna Andrés G Fernandez Manel Esteller 《Epigenetics》2014,9(6):829-833
A formalin-fixed paraffin-embedded (FFPE) sample usually yields highly degraded DNA, which limits the use of techniques requiring high-quality DNA, such as Infinium Methylation microarrays. To overcome this restriction, we have applied an FFPE restoration procedure consisting of DNA repair and ligation processes in a set of paired fresh-frozen (FF) and FFPE samples. We validated the FFPE results in comparison with matched FF samples, enabling us to use FFPE samples on the Infinium HumanMethylation450 Methylation array. 相似文献
84.
85.
Background
Recent studies point to a great diversity of non-ribosomal peptide synthesis systems with major roles in amino acid and co-factor biosynthesis, secondary metabolism, and post-translational modifications of proteins by peptide tags. The least studied of these systems are those utilizing tRNAs or aminoacyl-tRNA synthetases (AAtRS) in non-ribosomal peptide ligation. 相似文献86.
L I Kulikova G A Iatskiavichiute V S Tsvetkov Iu E Ershikova S P Gordienko 《Biulleten' eksperimental'no? biologii i meditsiny》1987,104(8):224-226
Antibodies to calcitonin, parathyroid hormone and cortisol are detected in acute stage of infection-caused bronchial asthma. The appearance of antibodies is paralleled by marked hypercalcaemia. The antibodies may bind excessive hormones in the blood, preventing further hormonal imbalance. Ten-day treatment with glucocorticoids decreased the amount of antibodies possibly due to normalization of hormonal secretion and restoration of their balance. As a result, calcium blood levels returned to normal. 相似文献
87.
J G Fukushima O Cascone J A Santomé M J Biscoglio de Jimenez Bonino 《International journal of peptide and protein research》1987,30(3):365-370
Reactivity of histidine residues in equine growth hormone to ethoxyformic anhydride was studied. The existence of two kinetically different sets was demonstrated: one of them including only the slow reacting histidine 169 (k = 0.164 min-1) and the other containing fast reacting histidines 19 and 21 (k = 0.892 min-1). A correlation between the decrease in the capacity to compete with 125I-labeled hormone for rat liver binding sites and the degree of ethoxyformylation of the fast group was found. Circular dichroism studies indicated no significant conformational changes in the protein with all three residues modified. These results fully agree with those obtained for bovine growth hormone which is further evidence supporting the vinculation of histidines 19 and/or 21 with the binding site of these hormones to their specific receptors. 相似文献
88.
89.
90.